The proposed research will investigate the intra- and intermodal processes involved in the development of sound localization abilities. The aim of the proposed resarch is to provide a better understanding of the basic processes involved in sound localization as well as extending our knowledge by illuminating deficits in these processes which are associated with very low birth weight (less than 1500 grams). Four experiments are proposed which employ cross-sectional and longitudinal methodlogies. Both healthy fullterm and preterm infants will be assessed from birth to 4 months of age. The studies are designed to examine sound localization at various levels of compleixty, ranging from simple discrimination of changes in the binaural cues which signal the direction of the sound to the ingetration of the auditory and visual modalities which occurs during sound localization Experiment I is designed to determine the age at which the infact is able to discriminate the binaural cues necessary for sound localization. A dichotic listening paradigm is employed with infant heart rate as the dependent measure. Experiment II will investingate the infant's developing ability to localize a souod source with a head turn when each binaural cue is manipulated independently and in combination. A free-field diotic listening paradigm will be employed. Experiment III will longitudinally assess the infant's ability to turn toward a sound from birth to 4 monts of age. Experiment IV will investigate the intermodal aspects of sound localization by adding a visual stimulus component to the sound localization paradigm. Measures of both head turning and visual behavior will be included. The longterm goals of this research would be to determine if iearly differences in the processes of sound localization relate to subsequent developmental outcomes such as delays in language development.